1. Field of the Invention
This invention relates to a hybrid-graft copolymer having a sulfopolyester grafted with an acid-functional polymer. The hybrid-graft copolymer is well-suited for use in hair care formulations. The hybrid-graft copolymer has excellent curl retention, even at high humidity, and may be formulated over a wide range of volatile organic component (VOC) content.
2. Description of the Related Art
A hair care product must meet a variety of requirements. Performance requirements include, for example, exhibiting fine spray pattern, good film formation, good holding power, prolonged curl retention, low stickiness and lack of powdering or flaking, being clear, transparent and glossy and easy to remove upon washing the hair with soap or shampoo. In addition, recent environmental legislation in some states requires hair care products to be formulated with a low content of volatile organic compounds (VOC). Polymer systems addressing at least some of these requirements are disclosed in the following patents:
U.S. Pat. No. 5,441,728 describes a blend of a water-soluble polymer, having a particular viscosity in water, with a latex of water-insoluble polymeric particles dispersed in water of a particular glass transition temperature. The latex and the water-soluble polymer interact with one another to provide a hair setting composition.
U.S. Pat. No. 4,985,239 describes a hair cosmetic composition containing a particulate polymer having an average particle diameter of from 0.005 to 0.2 .mu.. The particulate polymer is preferably in the form of a polymer latex. The particulate polymer can be blended in hair cosmetic compositions for shampoos, rinses, treatments, hair sprays, set lotions and the like. A conventional emulsion polymerization process cannot be used to prepare the particulate polymer.
U.S. Pat. No. 4,300,580 describes a hair grooming composition containing a linear polyester derived from a dicarboxylic acid, a diol and a difunctional monomer containing a --SO.sub.3 M group attached to an aromatic nucleus which is dissipatable in water and water-alcohol mixtures. The diol component of the polyester contains at least 20 mol % of a poly(ethylene glycol). Such formulations are fast drying and have good hair holding properties, but possess the disadvantage of being very difficult to remove from the hair.
U.S. Pat. No. 5,266,303 describes aerosol hair spray formulations based on a sulfonate-containing, water-dispersible or water-dissipatable linear polyester having a glass transition temperature of about 36.degree. C. to about 40.degree. C., a water-soluble polyvinyl lactam polymer, and water.
U.S. Pat. No. 5,158,762 describes a water-based hair spray composition capable of providing a fine finishing mist which provides a stiff resin film having excellent hair holding power, with superior shine, and feel, and within a relatively low drying time, approaching that of alcohol-based systems. The composition attains its attributes by including a predetermined blend of at least two hair spray resins, one being a water-soluble resin, and the other resin being a water-dispersible polyester or polyester amide.
EP Application No. 2 719 995 describes an aqueous cosmetic composition for hair setting based on the combination in an aqueous or low alcohol medium of a sulfonated polycondensation water dispersible group and a water-soluble copolymer containing one neutralized carboxylic acid group and by patterns including a cyclic ester group. The composition has excellent setting power and can be satisfactorily washed away with shampoo.
EP Application No. 0 687 459 A1 describes capillary compositions containing an aqueous dispersion of polymers, such as polyesters, polyamides or alkyds, as film forming agents. The polymers are prepared by radical polymerization of a radical monomer inside and/or partially on the surface of the preexisting particles of the polymer.
EP Application No. 0 705 595 A2 describes aqueous low VOC hair styling compositions containing at least one acrylic hair fixative resin and one or more plasticizing compounds selected from polycarboxylic acid esters and dimethiconecopolyols. Also described are low beading, low VOC hair styling compositions containing at least one surface tension reducing compound, at least one acrylic hair fixative resin, and at least one simethicone. Aqueous hair resin compositions containing at least one acrylic hair fixative resin and iodopropynyl-butylcarbamate are also described. An acrylic hair fixative resin contains an alkyl (meth)acrylate monomer, a hydroxyalkyl (meth)acrylate monomer, and a monoethylenically unsaturated monocarboxylic acid monomer.
Despite such efforts, there still exists a need for a hair care polymer composition which is compatible with a wide range of VOC and able to form suitable formulations at a broad range of solvent concentrations. In addition, there is a need for a hair fixing composition which exhibits superior curl retention, even at high humidity levels.